Pivoted implements having elongated members disposed for cooperative engagement about a pivotable joint are widely used. For convenience or to prevent injury to the user, some of these tools are provided with foldable handles so that the tool can be folded into a safe compact assembly when not in use. Prior art foldable tools generally comprise two elongated members, typically made of stamped or forged metal or other suitable material, disposed for cooperative engagement about the pivotable joint such as a screw or bolt arrangement. Typically, each member includes a jaw, having a working end and an opposed tang, and a handle conforming to the fingers or hands of the user. The handles are pivotally connected to the tang such that the jaws or blades are protectively nested within the handles when the handles are folded about the tangs.
Foldable pivoted tools of the type disclosed in the prior art are generally made entirely of metal. These items typically comprise various components requiring several distinct manufacturing steps followed by the assembling of sub-assemblies and the adjustment of pivoted parts for suitable operation. Examples of such foldable tools are described in U.S. Pat. No. 2,952,912, issued to Crawford on Sep. 20, 1960; U.S. Pat. No. 1,370,906, issued to Newton on Mar. 8, 1921; U.S. Pat. No. 1,461,270, issued to Garrison on Jul. 10, 1923; and U.S. Pat. No. 858,003, issued to Klever on Jun. 25, 1907. Patents '912, '906 and '003 illustrate examples of folding scissors, while the '270 patent discloses a pair of pliers with foldable handles.
As can be seen from these prior art patents, the handles of these conventional tools are pivoted to the tangs in one of two ways. One approach, disclosed in Crawford, Klever, and Garrison, consists of having each handle pivoted to the corresponding tang about an axis parallel to the axis of the tool (e.g., 36 and 22 in Crawford). In those cases, however, to permit adequate scissor-action, it becomes necessary to immobilize the handles with respect to the tangs. This typically requires the use of leaf springs (e.g., 42 in Crawford or 19 in Garrison) coacting with suitably cammed surfaces of the tangs to releasably prevent relative movement of the handles and the jaws. When it is desired to store the item away, the user needs to overcome the force of the spring or disengage the spring from a mating recess to permit folding of the handles.
A second approach to prevent unacceptable movement of the handles with respect to the tangs is disclosed in Newton. As shown in FIG. 1 of Newton, the pivots of the handles and tangs are disposed at right angles with the main pivot of the tool. As can readily be appreciated, unlike in Crawford and Garrison, normal scissor-action of the handles will typically not tend to rotate the handles about the pivot of the tangs. However, even with such right-angle configuration, it is preferable to unite more positively the handles and the tangs to prevent accidental folding of the handles for example when the scissors are being positioned by the user with respect to the item to be cut. Newton discloses that this can be accomplished using a leaf spring 6 coacting with a corresponding tang. This results in additional components which eventually increase manufacturing cost and may necessitate periodic adjustments under normal use of the tool.
The limitations identified in the foregoing make apparent that prior art methods used to manufacture pivoted foldable tools, such as scissors or the like, have various disadvantages. These prior art methods typically require assembling two members such as a pair of blades which have been previously manufactured separately and installing various other components for appropriate operation of the foldable scissors, thereby increasing material handling requirements which generally translate into higher unit cost. Thus, it appears desirable to provide foldable pivoted tools such as scissors or the like which can alleviate the problems associated with conventional manufacturing methods. That is, it is desirable to engineer foldable tools so that they lend themselves to functional assembling during, as opposed to subsequent to, the manufacturing process, or that otherwise reduce the number of operations required to manufacture these tools, while maintaining or improving all features typically desired by users of these tools.